W169 Air con theory

[Wingnuts]

W169 A Class 2005 on series.
Mine works but somethong I find confusing, any advice please?

On early models like mine
Red lamp Off = Air Con ON
Red lamp On = Dehumidifier Off
(later versions the lamp notification is reversed )

So what does that actually mean, it seems that the a/c compressor is running in either case but windows not being dehumidified if lamp is On???
If thats right then why does the book refer to a/c On or Dehumidifier Off???

Would it be more correct to just say that A/C is on when the blowerswitch is at position 1 or higher but the dehumidifier function can be switched off?

Also seems strange that for powered air flow from the vents you have to have the a/c pump running all the time even in cooler weather where a/c is not needed?

Thanks if someone can decipher this.

 

[eihtur]

Red lamp off...air con and dehumidifier on.
Red lamp on...air con and dehumidifier off.

 

[whitenemesis]

Display logic of function LED in the AC button (7)
For vehicles up to 31.5.05, the function LED is off when the refrigerant compressor is on.
For vehicles as of 1.6.05, the function LED is on when the refrigerant compressor is on.

Leave the a/c on all the time, that's how it's designed to work. In cold weather you still need to dehumidify the incoming air.

 

[Wingnuts]

My A150 is very nippy, revs to the redline no problem but with the AC on it can be sluggish especially on the many hills where I live, the compressor is quite noisy as well, at tickover especially. I dont usually use it in the winter but obviously where I live (Malta) its essential during the summer.
Hate to think what a terrible job it would be to change any ac components on this car. (would rank alongside changing a starter motor or drive belt I guess).

Thanks for replies and clarifying the lamp